Submarine groundwater discharge (SGD) into the Yellow Sea revealed by super(228)Ra and super(226)Ra isotopes: Implications for global silicate fluxes

• Published in: Earth and planetary science letters 2005-08, Vol.237 (1-2), p.156-166
• Main Authors: Kim, Guebuem, Ryu, Jae-Woong, Yang, Han-Soeb, Yun, Seong-Taek
• Format: Article
• Language: English
• Subjects: Marine
• ISSN: 0012-821X
• DOI: 10.1016/j.epsl.2005.06.011

We estimated the magnitude of submarine groundwater discharge (SGD) into the Yellow Sea, which is one of the largest continental shelves in the world, using super(226)Ra and super(228)Ra isotopes. On the basis of super(228)Ra and super(226)Ra mass- balance models, we estimated the advective flux of super(226)Ra through SGD to be 270 x 10 super(12) dpm yr super(- 1) in the Yellow Sea. Using this super(226)Ra flux and the measured super(226)Ra activity in coastal groundwater, the submarine discharge of groundwater (mostly brackish groundwater) was calculated to be at least 40% of the river-water input (2.3 x 10 super(11) m super(3) yr super(- 1)). Then, on the basis of the SGD and the concentration of Si in coastal groundwater, we estimated the flux of Si through SGD to be 20-100% of that associated with river discharge (23 x 10 super(9) mol yr super(- 1)). This large SGD is likely to be due to the high tidal range (up to 10 m) and the wide distribution of sandy sediments in the Yellow Sea, favorable for the recirculation of seawater through bottom sediments and rocks. This result from such a large area implies that the Si flux through SGD may be significant on a global scale.